FDA does regulate cosmetics components, and FTC regulates what claims they can make. It’s hard to make a binary decision that one thing is a drug and something else isn’t. You can appreciate there is a spectrum of side effects with moisturizer and sunblock on one end, supplements in the middle, and chemotherapy drugs on the other end.

Personally, I think that Americans simply don’t treat skin cancer as seriously as they should, and so the market has not provided more choices.